This invention relates to an information processing method and apparatus, a program, and a recording medium and, more particularly, to an information processing method and apparatus, a program and a recording medium configured for maintaining continuity of moving pictures in a reproducing domain.
Recently, a variety of types of optical discs have been proposed as a recording medium that can be removed from a recording apparatus. These recordable optical discs have been proposed as a large capacity medium of several GBs and are thought to be promising as a medium for recording AV (audio/video) signals, such as video signals. Among the sources of the digital AV signals (supply sources) to be recorded on this recordable optical disc, there are CS digital satellite broadcasts and BS digital broadcasts. Additionally, ground wave television broadcasts of the digital system have also been proposed for future use.
The digital video signals, supplied from these sources, are routinely compressed under the MPEG (Motion Picture Experts Group) 2 system. In a recording apparatus, a recording rate proper to the apparatus is set. If digital video signals of the digital broadcast are recorded in the conventional image storage mediums for domestic use, digital video signals are first decoded and subsequently bandwidth-limited for recording. In the case of the digital recording system, including, of course, the MPEG1 video, MPEG2 video and DV systems, digital video signals are first decoded and subsequently re-encoded in accordance with an encoding system for the recording rate proper to the apparatus for recording subsequently.
However, this recording system, in which the supplied bit stream is decoded once and subsequently bandwidth-limited and re-encoded prior to recording, suffers from deteriorated picture quality. If, in recording compressed digital video signals, the transmission rate of input digital signals is less than the recording rate for the recording and/or reproducing apparatus, the method of directly recording the supplied bit stream without decoding or re-encoding suffers from deterioration in the picture quality only to the least extent. However, if the transmission rate of the input digital signals exceeds the recording rate of the recording and/or reproducing apparatus, it is indeed necessary to re-encode the bit stream and to record the re-encoded bit stream so that, after decoding in the recording and/or reproducing apparatus, the transmission rate will be not higher than the upper limit of the disc recording rate.
If the bit stream is transmitted in a variable rate system in which the bit rate of the input digital signal is increased or decreased with time, the capacity of the recording medium can be exploited less wastefully in the case of a disc recording apparatus adapted for transiently storing data in a buffer and for recording the data in a burst fashion than in the case of a tape recording system having a fixed recording rate imposed by the fixed rpm of the rotary head.
Thus, it may be predicted that, in the near future when digital broadcasts are to become the mainstream, an increasing demand will be created for a recording and/or reproducing apparatus in which broadcast signals are recorded as digital signals, without decoding or re-encoding, as in a data streamer, and in which a disc is used as a recording medium.
In reproducing data recorded on a recording medium in the above-described recording apparatus, there is known so-called skip reproduction in which reproduction is continued up to a preset picture and a picture temporally spaced apart from the preset picture is reproduced next. This skip reproduction has a drawback that temporal continuity is lost in the reproduced pictures.